To date, a predetermined function has been assigned in advance to a long press operation that is performed on an input device, such as a button, a touch panel, etc., and the assigned function has been executed when the long press operation is actually performed. A long press operation is an operation in which an operation input time to an input device is a predetermined time or more. In general, a “long-press-operation determination time” for determining whether an input operation is a long press operation or not is set in advance, and if operation input time exceeds the long-press-operation determination time, that operation is determined to be a long press operation. For the long-press-operation determination time, for example, a value of about one second is set.
If the operation input time has not reached the long-press-operation determination time, that operation is determined to be a short press operation. Normally, a function that is different from the function assigned to a long press operation is assigned to a short press operation. If an operation input time is short, which is less than the long-press-operation determination time, the function assigned to the short press operation is executed. Accordingly, if a user accidentally has performed the long press operation without the user's intention, and as a result, the function assigned to the long press operation is performed, or the like, it has been difficult for the user to determine whether the function was performed as a result of the long press operation or not.
For example, Patent Literature 1 has disclosed a method of informing a user of whether an executed function is associated with a short press operation or a long press operation by changing vibration patterns of a vibration device depending on whether a long press operation has been detected or a short press operation has been detected.